Resonance forms are only multiple representations of the same structure. Hydrocarbons containing planar rings form one double and two single bonds are called aromatic hydro- carbons. Carbon-carbon bonds are written in the polygons. Solution Resonance forms are only multiple representations of the same structure. Hydrocarbons containing planar rings form one double and two single bonds are called aromatic hydro- carbons. Carbon-carbon bonds are written in the polygons..